In many Internet Protocol (IP) network configurations, a host device may be coupled to a Layer 3 routing device (for accessing a Wide Area Network) through a Layer 2 (L2) switching device. An example of one such Layer 2/Layer 3 network is a Digital Subscriber Line (DSL) network, where multiple DSL customers are connected by a Digital Subscriber Access Multiplexer (DSLAM) at a phone company's central location links to a high-speed ATM line. The ATM line in turn may be coupled to a Layer 3 routing device, which serves to route the customers' requests for content to the appropriate location in the network. The router may provide IP data (such as Internet TV or the like) from an ISP to one or more of the connected customers. It is often common to use multicast transmissions to transmit content simultaneously from one source to multiple destinations. When performing multicast communications, a source transmits content to a Group Destination Address (GDA). Each device that is a member of the group associated with the GDA retrieves the data.
It is important to ensure that only authorized customers receive access to controlled content. Because group membership is constantly changing, it is often difficult to ensure that content is not mis-delivered.